Refactoring WebSearch and going from End to end again.

I refactored WebSearch, to prepare the work to create a HttpClient that retrieves the results from any web page (not only google)
Moreover, since Google API has a limit in the number of requests we can do on a daily basis, I thought that we could switch to Bing if necessary. I also prepared the work to create a BingSearchClient and integrate it easily.

The HttpClient will come later. 
The program should now work from end to end, and generate slides with the URLs found on google.